Air cushion trunk for ground effect machines

ABSTRACT

An air cushion trunk sealing system for ground effect machines is provided to prevent air leakage from the trunk during periods of operation and parking when the primary power of the machine or craft is turned off. This system is composed of an inner tube type liner (which may be, and preferably is, constructed of multiple cells) which is collapsed, doubled and attached to the underside of the craft and within the trunk. Before the trunk air is turned off, air of higher pressure than trunk pressure is routed into the collapsed inner tube to inflate it. As this inner tube inflates, it replaces the trunk air while the trunk air flow is still providing craft support. When the inner tube is fully inflated, the air to the trunk is fully diverted overboard and the inner tube now supports the craft. The inner tube valve is closed to contain the air and the trunk air may be turned off.

United States Patent 1 1 3,727,716 Jenkins [451- Apr. 17, 1973 AIR CUSHION TRUNK FOR GROUND Primary Examiner-Kenneth H/Betts EFFECT MACHINES [75] Inventor: Dave H. Jenkins, Marietta, Ga.

[73] Assignee: Lockheed Aircraft Corporation,

Burbank, Calif.

[22] Filed: Apr. 5, 1971 [21] App1.No.: 131,274

[52] U.S Cl ..180/124, 180/128 [51] int. Cl ..B60v 3/08 [58] Field of Search ..180/124, 128

[56] References Cited UNITED STATES PATENTS 3,414,077 12/1968 Earl ..180/128 3,481,424 12/1969 Barr ....180/124 3,524,517 8/1970 LaFleur.. ..180/124 3,595,336 7/1971 Perez ..180/124 X Attorney-John J. Sullivan and G. C. Sullivan 5 7 ABSTRACT An air cushion trunk sealing system for ground effect machines is provided to prevent air leakage from the trunk during periods of operation and parking when the primary power of the machine or craft is turned off. This system is composed of an inner tube type liner (which may be, and preferably is, constructed of multiple cells) which is collapsed, doubled and attached to the underside of the craft and within the trunk. Before the trunk air is turned off, air of higher pressure than trunk pressure is routed into the collapsed inner tube to inflate it. As this inner tube inflates, it replaces the trunk air while the trunk air flow is still providing craft support. When the inner tube is fully inflated, the air to the trunk is fully diverted overboard and the inner tube now supports the craft. The inner tube valve is closed to contain the air and the trunk air may be turned off.

10 Claims, 7 Drawing Figures PATENTEBAPR 1 71973 SHEET 1 UF 4 DAVE H. JENKINS INVENTOR.

Attorney AIR CUSHION TRUNK FOR GROUND EFFECT MACHINES This invention relates to ground effect machines or vehicles of the type which employ an air cushion trunk as opposed to a skirt to contain air and to control its discharge on and against the reaction surface, and more particularly to improvements in such vehicles whereby parking and towing operations are facilitated during power-off condition of the vehicle.

While air cushion trunks have been employed on a fairly wide basis, maximum advantage has not been taken of them as vehicle-supporting devices during power-off parking and towing operations. During power-off, the trunk collapses and it is generally recognized that auxiliary support means is desirable at this time in order to prevent damage to the vehicle as it would otherwise settle to the ground or other supporting surface. Where vehicle support has been provided during power-off, it has been accomplished by independent means such as pontoons, outriggers and the like which may be flexible and air-inflated.

In converting from air cushion support to power-off auxiliary support and vice versa, damage may nevertheless occur unless special means is provided to coordinate the transfer of vehicle support. In prior arrangements, the complexity of such special means varies with the type of the several auxiliary supporting schemes employed.

The present invention is directed toward improvements in this area of the art. In essence, it is herein proposed to integrate the air cushion and auxiliary support mechanisms so that they function as a unit and thereby permit the smooth transmission to and from the air cushion phase and the auxiliary support phase. Moreover, this is accomplished by means of and through the maintenance of a constant trunk expanded condition so that its air confining and entrapping function is available for use at all times during its association with and in proximity to a supporting and/or reaction surface. This not only affords advantages in the parking condition of the vehicle, regardless of the type of supporting surface, but also facilitates the towing thereof. In each operation, the vehicle, and more particularly the trunk, is exposed to minimum danger of damage.

More specifically, this invention contemplates a modification of the air cushion trunk to include an in ternal flexible and inflatable tube. The inner tube is appropriately connected to a source of fluid supply whereby it may be inflated when desired causing it to expand within the trunk forcing out the air within the trunk and eventually filling the entire interior of the trunk. During this operation, the air supply to the .trunk continues until such time as the inner tube completely fills the interior of the trunk at which time air supply may be discontinued. Thus, the valving of fluid to the inner tube and to the trunk interior is coordinated and synchronized to effect the smooth transition.

The inner tube may be, and in the preferred form is, comprised of multiple sections or cells which are appropriately isolated one from the other. This gives greater reliability and also where desired affords an arrangement whereby the level of the vehicle may be controlled with respect to a support or other surface simply by regulating or varying the fluid pressure in the several cells.

While this mechanism as contemplated hereby may be applied to ground effect machines or vehicles generally, it is especially applicable to aircraft where the trunk is to be employed as the landing gear system. When such aircraft is airborne, i.e., supported by the airstream as opposed to the ground reaction effect, it is desirable that the trunk and inner tube or tubes be totally collapsed and configured in such a way as to fold snugly within or against the adjacent external surface of the aircraft and thereby preserve the clean aerodynamic lines of the aircraft during flight.

With the above and other objects in view, as will be apparent, this invention consists in the construction, combination and arrangement of parts all as hereinafter more fully described, claimed and illustrated in the accompanying drawings, wherein:

FIG. 1 is a bottom perspective view of an aircraft modified to include an air cushion trunk installed on the belly of the fuselage thereof, such trunk being illustrated in the fully inflated condition;

FIG. 2'is a schematic plan view illustrative of the trunk configuration and associated source of air supply;

FIG. 3 isa view similar to FIG. 2 of the inner tube arrangement conformed to the air cushion trunk to show primarily the plumbing and valving necessary for the inflation and deflation thereof;

FIG. 4 is a section taken along line 4-4 of FIG. 3 to show a transverse section through the air cushion trunk and adjacent inner tube and associated portion of the aircraft fuselage, the trunk being fully inflated and the inner tube beingin the deflated condition corresponding to the operation of the aircraft in ground reaction effect;

FIG. 5 is a similar view showing the inner tube as it is being inflated corresponding to the transition of vehicle support from the trunk during power-on to the auxiliary device during power-off whereby the inner tube is made to fill the air cushion trunk, forcing-the internal air thereof out;

FIG. 6 is a similar view showing the fully inflated condition of the inner tube whereby it maintains the trunk in the fully expanded condition corresponding to the power-off condition of the vehicle whereby it is parked and in a condition facilitating its being towed; and

FIG. 7 is an isometric view at an appreciably larger scale of the peripheral edge portion of the trunk and inner tube to show the method and means of their attachment to the aircraft fuselage as well as their particular design configuration to facilitate their operation as contemplated herein.

As stated hereinabove, the invention may be embodied in any type of vehicle. As shown by way of example in the accompanying drawings, it is incorporated in an airplane 10 which includes a main body or fuselage 11, adjacent Wings 12 and engines I3 or other power drive means. An air cushion trunk 14 fabricated of flexible and inflatable material is secured to the undersurface of the fuselage 11 by a clamp. 15 which is also employed to secure each inner tube segment 16 within the trunk 14 to the aircraft fuselage l l.

The clamp 15 is formed by a base strip 17 made of rubber or the equivalent having a sufficient hardness to take the necessary compression loads, but still be flexible enough to be fitted to the fuselage contour. This feature eliminates the requirement for expensive complicated machining that would otherwise be necessary to provide mating of the attachment provided by the clamp with the aircraft contour.

Each inner tube segment 16 is fabricated as a single, sealed unit of elastic material with a bulbed tab 18 at and continuously along its opposite longitudinal edges. This bulbed tab 18 is attached to the base strip 17 by means of and through clamp elements 19 connected to the base strip 17 and aircraft structure 11 by screws or bolts 20. Each tube segment 16 is thereby made to stretch around the aircraft fuselage 11 with its opposite ends in substantial abutment against the next adjacent segment end.

The trunk 14 is similarly provided with a bulbed circumferential edge 21 adapted to be attached to base strips 17 by means of and through clamp elements 22 and bolts 23 similar to those 19 and employed with respect to the inner tubes 16. The trunk 14, however, is formed of one continuous elastic fabric of annular configuration with a bulbed edge 21 defining each peripheral edge and coacting with an adjacent clamp element 22 as described. After the larger, outer circumferential edge 21 of the trunk 14 has been attached all the way around the fuselage 11, the smaller, inner circumferential edge 21 of the trunk 14 is stretched and attached in a similar manner. The several inner tube segments 16 are sized and configured to be contained within and substantially fill the area thus defined by the annular trunk 14. At the same time the trunk 14 surrounds an area 11' of the aircraft fuselage of predetermined size and shape, preferably oblong or rectangular.

Each inner tube segment 16 includes a connecting line 24 from a common duct 24' extending from an air manifold or auxiliary compressor 25 inside of the fuselage 11, for example. Each line 24 opens at its other end within the tube segment 16. A flow control/shut-off valve 26 is operatively incorporated in each line 24 and an exhaust line 27 extends from each line 24, being located between the valves 26 and the associated tube segment 16 and terminating in an overboard port 28. An outflow deflation valve 29 is operatively incorporated in each line 27. Since the tube seg-.

ments or cells 16 are sealed in manufacture, the possibility of air leakage is very remote. The bulbed edges 21 -of the air cushion trunk 14 provide the required strength and air seal without requiring a penetration of the trunk materials. I

Also connected to the common duct 24' is an auxiliary line 30 which extends therefrom and terminates in an open port 31 externally of the aircraft 10 and beyond the trunk 14 as well as a spur line 32 which extends from the duct 24' terminating in an open port 33 externally of the aircraft 10 but within the area 34 defined by the trunk 14, fuselage area 11' and the adjacent reaction area. An on-off valve 35 and 36, respectively, is operatively installed in each line 30 and 32 adjacent the respective ports 31 and 33.

Referring now specifically to FIG. 2, inflation of the trunk 14 is accomplished through a connecting duct 37 from a suitable source of air which in some cases may be bleed air from the engines 13. For present purposes, however, this source is preferred to be supplied from the exterior of the aircraft 10 through suitable openings 38 communicating with a plenum 39 within the aircraft 10. A fan 40 mounted within the duct 37 and powerdriven by a motor 41 draws external air into the plenum 39 and duct 37. An overboard exhaust line 42 with a pressure relief valve 43 is connected in the duct 37 between the trunk 14 and each fan 40. Air pulled into each plenum 39 by the associated fan 40 is thus forced into the trunk 14 through the ducts 37 at a predetermined pressure, for example on the order of 5 psig. This air is then ducted through the trunk 14 to the periphery where it is exhausted through a plurality (which may be in the hundreds) of small holes 44 to form an air jet curtain. This jet curtain causes a cushion pressure of about 2.5 psig to develop in an air cushion area 34.

When it is desired to park the aircraft 10, the fans 40 will be running and a constant supply of air will be available through the ducts 37 for full inflation of the trunk 14 and a cushion of air in the area 34. At this time the inner tube cells 16 will be in a collapsed position against the underside of the fuselage 1 l, the position illustrated in FIG. 4. The onboard auxiliary air compressor 25 is started with the several valves 26 closed and valve 35 open to exhaust compressor air overboard. With the several valves 29 and valve 36 closed the several valves 26 are opened and valve 35 is slowly closed. This allows air of a predetermined pressure, for example, about l5 psig, from compressor 25 to inflate all of the inner tube cells 16 through the several lines 24. When the cells 16 are being inflated, they commence to fill the trunk 14 and'start to close off the air flow through the many small holes 44 in the bottom surface of trunk (FIG. 2) thereby producing a reduction in air flow from the fans 40 and an increase in pressure. As this occurs, the pressure build-up in the trunk 14 causes the pressure relief by-pass valves 43 to open allowing air in the ducts 37 to be diverted overboard, thus preventing fan stalling. When the inner tube cells 16 are fully inflated, they fill the trunk 14 gradually exhausting the air therefrom. The valves 26 are then closed to provide a leakproof air support of the aircraft 10. The fan motors 41 may then be turned off.

Aircraft support for power-off towing is provided simply by pressurizing the air cushion area 34 adjacent the aircraft fuselage portion 11 encircled by the trunk 14. This is accomplished simply by connecting a suitable source of air pressure to the port 31 and opening valves 35 and 36 (valves 26 and 29 being closed) whereby a cushion of air builds up in the area 34 which eventually serves to completely support the aircraft 10. A conventional tug can be utilized to tow or move the aircraft 10.

To transition from the power-off parked condition to an operational air cushion support condition (valves 35 and 36 being closed) the fan motors 41 are started. Since the inner tube cells are inflated, they fill the trunk 14 thus causing the fan air to be diverted overboard through valves 43 and line 42. The several valves 29 are then opened allowing the inner tube cell air to be exhausted overboard through their respective exhaust ports 28. As the air in the several inner tube cells 16 thus exhausts, the fan air entering the trunk 14 through the ducts 37 is allowed to flow between the walls of the cells 16 and the trunk 14 providing trunk support. In order to assure such air flow between cells 16 and trunk 14 and the concurrent contraction of the several inner tubes 16 to the position shown in FIG. 4, special means is provided between adjacent surfaces of the inner tubes 16 and trunk 14. Preferably, this is accomplished by means of and through grooves 45 or the equivalent formed in the surfaces of each of the tube cells 16. When the inner tube cells 16 are completely contracted, the system is now in a normal air operational air cushion support condition.

While the invention has been hereinabove illustrated and described in what is believed to be its best and most practical form under presentday conditions, it is recognized that under other conditions this form would be modified. No attempt has been made to specifically incorporate any of such other forms in this disclosure in the interest of clarity of the total inventive concept. The claims are relied upon to cover these other forms generally.

What is claimed is:

1. In a ground effect machine the combination with an air cushion trunk having a multiplicity of perforations therein adapted to discharge air therefrom in a downward direction relative to said machine, of at least one inner tube disposed within said trunk, a clamp assembly secured at and along the undersurface of said machine adjacent said trunk, said clamp assembly including elements adapted to receive and secure the respective marginal edge portions of said trunk and each saidinner tube, a first fluid pressure means operatively connected to said trunk and a second fluid pressure means operatively connected to'each said inner tube for. communication with the respective interiors thereof, a first overboard port between said first fluid pressuremeans and said trunk, a second overboard port between said .second fluid pressure means and each said inner tube, first control valves operatively 7 connected between' said first fluid pressure means and said trunk and between said trunk and said first overboard port and second control valves operatively connected between each second fluid pressure means and each said inner tube and between each said inner tube operated in the alternative to thereby selectively and concurrently. provide air under pressure to and remove annular and said clamp assembly is associated as aforesaid with each peripheral edge of said trunk.

3. The combination of claim. 2 including an auxiliary air line terminating at one end in a port located externally of said trunk and said machine and communicating at its other end with a spur line having a port located externally of said machine and within the area defined by said annular trunk, and a shut off control valve in each of said auxiliary and spur lines between said ports. 7 v

4. The combination of claim 3 including a common duct mounted between said second fluid pressure means and each said inner tube upstream of their respective control valves and wherein the associated ends of said auxiliary air line and saids'pur line aforesaid communicate with said common duct.

5. The combination of claim 1 wherein multiple inner tubes are employed in contiguous relation.

continuous recesses therein adapted to mate with said trunk and inner tube marginal edge portions.

7. The combination of claim 1 wherein said first fluid pressure means includes an opening in said machine to receive ambient external air, a duct connecting said opening to the interior of said trunk, an overboard exhaust outlet in said duct, a pressure relief valve in said exhaust outlet. and a power-driven fan operatively mounted within said duct between said opening and said outlet.

8. The combination-of claim 1 including channels between the adjacent surfaces of said trunk and each said inner tube when the latter is pressurized as aforesaid and disposed proximate the former.

9. The combination of claim 8 wherein said channels are formed by recesses provided in each said inner tube surface. 4

10. The combination of claim 1 wherein each said inner tube is fabricated of an elastic and configured to lie flush against the surface ofsaid machine when all air is removed from the interior. thereof. 

1. In a ground effect machine the combination with an air cushion trunk having a multiplicity of perforations therein adapted to discharge air therefrom in a downward direction relative to said machine, of at least one inner tube disposed within said trunk, a clamp assembly secured at and along the undersurface of said machine adjacent said trunk, said clamp assembly including elements adapted to receive and secure the respective marginal edge portions of said trunk and each said inner tube, a first fluid pressure means operatively connected to said trunk and a second fluid pressure means operatively connected to each said inner tube for communication with the respective interiors thereof, a first overboard port between said first fluid pressure means and said trunk, a second overboard port between said second fluid pressure means and each said inner tube, first control valves operatively connected between said first fluid pressure means and said trunk and between said trunk and said first overboard port and second control valves operatively connected between each second fluid pressure means and each said inner tube and between each said inner tube and its second overboard port aforesaid, said first and second control valves each being adapted to be operated in the alternative to thereby selectively and concurrently provide air under pressure to and remove air from the interior of said trunk and the interior of each said inner tube respectively.
 2. The combination of claim 1 wherein said trunk is annular and said clamp assembly is associated as aforesaid with each peripheral edge of said trunk.
 3. The combination of claim 2 including an auxiliary air line terminating at one end in a port located externally of said trunk and said machine and communicating at its other end with a spur line having a port located externally of said machine and within the area defined by said annular trunk, and a shut off control valve in each of said auxiliary and spur lines between said ports.
 4. The combination of claim 3 including a common duct mounted between said second fluid pressure means and each said inner tube upstream of their respective control valves and wherein the associated ends of said auxiliary air line and said spur line aforesaid communicate with said common duct.
 5. The combination of claim 1 wherein multiple inner tubes are employed in contiguous relation.
 6. The combination of claim 1 wherein said clamp assembly includes a base strip and a pair of clamp elements each removably secured to said base strip one to overlie and engage said marginal edge portion of said trunk and the other to overlie and engage said marginal edge portion of each said inner tube, the adjacent faces of said base strip and each said clamp elements having continuous recesses therein adapted to mate with said trunk and inner tube marginal edge portions.
 7. The combination of claim 1 wherein said first fluid pressure means includes an opening in said machine to receive ambient external air, a duct connecting said opening to the interior of said trunk, an overboard exhaust outlet in said duct, a pressure relief valve in said exhaust outlet, and a power-driven fan operatively mounted within said duct between said opening and said outlet.
 8. The combination of claim 1 including channels between the adjacent surfaces of said trunk and each said inner tube when the latter is pressurized as aforesaid and disposed proximate the former.
 9. The combination of claim 8 wherein said channels are formed by recesses provided in each said inner tube surface.
 10. The combination of claim 1 wherein each said inner tube is fabricated of an elastic and configured to lie flush against the surface of said machine when all air is removed from the interior thereof. 